[alsa-devel] [RFC] ALSA vs. dedicated char device for a USB Audio Class gadget driver

Clemens Ladisch clemens at ladisch.de
Tue May 19 13:01:07 CEST 2009

Laurent Pinchart wrote:
> On Monday 18 May 2009 10:39:24 Clemens Ladisch wrote:
> > The ALSA API doesn't give you access to the SOF clock.
> Does the ALSA API give applications access to the audio clock ?

ALSA wakes up the application (if it's blocked) whenever a sound card
interrupt happens, i.e., at period boundaries.  At all times, you can
get the current sample position by calling snd_pcm_delay().

> As Alan Stern mention in his e-mail, does ALSA allow an application to
> resample audio from an ALSA source (microphone on sound card 1) before
> sending it to an ALSA sink (speaker on sound card 2) ?

It is possible, if the application monitors the speed of both devices.

Best regards,

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